Silent call pager

ABSTRACT

A pager that produces a vibratory alerting signal when a paging signal is received. Vibrating motion is created by a motor, internal to the pager, rotating a weight. The rotating weight initially presents a small torque load to the motor, but subsequently a large vibrating motion is created because the center of gravity of the rotating weight moves further away from the axis of rotation due to centrifugal force.

United States Patent 119 Feder Oct. 7, 1975 SILENT CALL PAGER 3,691,4099/1972 Kobayashi 310/81 3,757,148 9/1973 Philibert 310/81 Inventor:Alvin Feder, Skokie, lll.

Assignee: Motorola, Inc., Chicago, 111.

Filed: Aug. 5, 1974 Appl. No.: 492,375

US. Cl 340/311; 340/407 Int. Cl. H04M 11/02 Field of Search 340/311,407, 271; 310/50, 310/51, 81, DIG. 1; 116/115, DIG. 17; 343/225 [56]References Cited UNITED STATES PATENTS 3,017,631 l/1962 Fink et a1343/225 3,618,070 11/1971 Kagan 340/311 3,623,064 11/1971 Kagan 340/311Primary Examiner-Thomas B. Habecker Assistant Examiner-James .l. GroodyAttorney, Agent, or FirmEugene A. Parsons; Vince Rauner 1 ABSTRACT Apager that produces a vibratory alerting signal when a paging signal isreceived. Vibrating motion is created by a motor, internal to the pager,rotating a weight. The rotating weight initially presents a small torqueload to the motor, but subsequently a large vibrating motion is createdbecause the center of gravity of the rotating weight moves further awayfrom the axis of rotation due to centrifugal force.

8 Claims, 2 Drawing Figures U.S. Patent Oct. 7,1975

SILENT CALL PAGER BACKGROUND OF THE INVENTION In standard pagingsystems, a signal is transmitted to alert a person to the fact that thebase station wishes to communicate with him. The transmitted signal isreceived by the pager and identified as being intended for a particularreceiver. If the identification is positive, an

alerting signal is generated which indicates to the user that he isbeing paged. The alert signal can either last.

SUMMARY OF THE INVENTION It is an object of this invention to illustratea vibratory pager that operates with less battery current drain.

Another object of this invention is to provide a silent call pager whichcreates a large vibratory motion while conserving battery current.

Still another object of this invention is, to use centrifugal force todisplace the center of gravity of a weight to generate a large vibratorymotion.

A motor, which is rigidly mechanically coupled to the frame of a pager,is activated when the pager receives a paging signal that is positivelyidentified. The motor rotates a drive shaft about an axis of rotationand the drive shaft has a weight attached to it. The center of gravityof the weight is close to the axis of rotation when the motor isnonoperative and the pager is in an upright position. When the motorrotates, the weight moves due to centrifugal force so that the center ofgravity of the weight is now substantially further away from the axis ofrotation. Thus the weight presents a low initial starting torque to themotor, but also creates a large vibratory motion due to the rotationalmovement of the center of gravity of the weight about the axis ofrotation at a greater distance.

DESCRIPTION OF THE DRAWINGS Referring to the drawings:

FIG. 1 is a pictorial view of a silent call pager with part of theexternal casing removed to show a vibrator mechanism; and

FIG. 2 is an enlarged pictorial side view of the vibrator mechanismshown in FIG.- 1.

DETAILED DESCRIPTION OF THE INVENTION nents which perform the functionsof receiving a paging radio signal, identifying the paging signal sothat only intended signals will activate the pager, and generating anelectrical signal to activate a motor. Since the electronic componentson PC board 13 are not part of the invention herein disclosed and areadequately described by the prior art, they will not be described in anydetail. v

Referring to FIG. 1, a motor 15 is rigidly attached to PC board 13 by abracket 14. Since 'PC board 13 is rigidly attached to case of the pager,the motor is therefore mechanically coupled to the pager. The

motor is also electrically connected (not shown) to components on PCboard 13 and is rendered operative by receiving voltage from PC board 13when a properly identified paging signal is received by the electroniccomponents on PC board 13. The motor 15 may be rendered operative byapplying a constant DC voltage to the motor, by applying DC pulses tothe motor, or by applying an AC signal to the motor. A battery 12supplies the power to operate the electronic components on printedcircuit board 13 and battery 12 also supplies the power to operate motor15. A drive shaft 16 is attached to motor 15 and is rotated by motor 15about an axis of rotation 19. In the specific embodiment shown in FIG.1, axis of rotation 19 is coincident with the axis of drive shaft 16,however the invention disclosed is not limited to having the drive shaftrotated about its own axis. Drive shaft 16, for example, could have itsaxis horizontally displaced from axis of rotation 19 and still berotated about axis of rotation 19 by motor 15.

A weight 17 is shown in FIGS. 1 and 2 and consists of two identicalgenerally L-shaped solid sections which are oppositely outwardly facingand are rigidly jointed together at the top of their vertical legs by ahorizontal crossbar. Each L-shaped section is symmetrically positionedwith respect to a vertical line bisecting and perpendicular to thehorizontal crossbar.

The separation between the L-shaped sections is greater than the widthof drive shaft 16, to provide clearance for rotation of weight 17 aboutdrive ,shaft 16. The bottom section of the horizontal leg of bothidentical solid sections has a radius of curvature extending from theoutward vertical tip of the horizontal leg to the bottom of the verticalleg. A pivot pin 18 is attached to the vertical legs of the two solidL-shaped sections of weight 17, and pin 18 is parallel to and below thehorizontal crossbar of weight 17. Weight 17 is capable of pivotal motionabout pivot pin 18. Pivot pin 18 extends perpendicular through driveshaft 16 and positions weight 17 such that axis of the rotation 19remains fixed midway between the two L-shaped sections of weight 17. Acenter of gravity 20 of weight 17 is shown coincident with therotational axis 19 of drive shaft 16 and close to pivot pin 18, howeverthe invention disclosed is not limited to the coincidence or proximityof center of gravity 20 to the rotational axis or pivot pin 18. Otherembodiments wherein the pivot means consists of a hinge instead of pivotpin 18 and the center of gravity of weight 17 is not originallycoincident with axis of rotation 19 are within the scope of theinvention.

FIG. 2 is an enlarged sideview drawing of the vibrating mechanism shownin FIG. 1. When motor 15 is rendered operative by the pager receiving aproper paging signal, motor 15 starts to rotate drive shaft 16. Weight17 then also begins to rotate since it is attached to drive shaft 16 bypivot pin 18. Weight 17 presents a small initial torque load to motor 15since its center of gravity 20 is initially coincident with axis ofrotation 19. As motor 15 continues to rotate, weight 17 will pivot onpivot pin 18 and move to a position generally referred to as 17' (showndotted) in H6. 2, because of the effect of centrifugal force. Whenweight 17 has moved to position 17, its center of gravity 20 is nolonger coincident with axis of rotation 19 and is now in a position 20'.Pivot pin 18 and position 20 lie in a plane perpendicular to axis ofrotation 19. Since the center of gravity of weight 17 is now displacedfrom axis of rotation 19, the rotation of motor 15 now createssubstantial vibratory motion due to the rotation of a nonsymmetricalmass. If weight 17 was permanently mounted in position 17' to driveshaft 16, the initial' starting torque of motor 15 would besubstantially higher and therefore motor 15 would require a largerstarting current.

The amount of centrifugal force necessary to cause weight 17 to pivotabout pivot pin 18 is determined by the proximity of center of gravity20 to pivot pin 18. While the particular embodiment shows a closeproximity of center of gravity 20 to pivot pin 18, the invention is notlimited to such proximity. A rotation of a weight which causes any shiftin the position of the center of gravity of a weight with respect to theaxis of rotation, such that a first original at rest position of thecenter of gravity is closer to the axis of rotation, than a second inmotion position of the center of gravity, comes within thescope of theinvention.

Thus a vibratory pager which has a low initial starting torque, butdevelops a substantial vibratory motion, has been disclosed. The lowinitial starting torque serves to substantially reduce the motorstarting current and thus reduce the total current drain on the batteryin a portable pager. Therefore the battery life is extended by the useof centrifugal force.

While this invention has been described with respect to a particularembodiment, the underlying inventive principles are not meant to belimited to such an embodiment. It is obvious that one skilled in the artmay make additional modifications to the invention disclosed herein, butall such modifications which retain the basic inventive ideas disclosedand claimed herein are within the scope of this patent. v

I claim:

1. A vibratory pager including:

a pager case;

a motor being responsive to receiving a paging signal and beingmechanically coupled to said pager case;

drive shaft means attached to said motor and capable of being rotatedabout an axis of rotation by said motor; i I

weight means;, v I

connection means for attaching said weight means to said drive shaftmeans, such that said weight means has a center of gravity with a'firstdistance from the axis of rotation when said drive shaft is not beingrotated, and said weight means moves, when said drive shaft means isbeing rotated, such that the center of gravity of said weight means is asecond distance from the axis of rotation, said second distance beinglarger than said first distance.

2. The pager as claimed in claim 1 wherein the axis of said drive shaftmeans is coincident with the axis of rotation.

3. The pager as claimed in claim 2 wherein said con-l nection meansincludes a pivot pin attached to said drive shaft means.

4. The pager as claimed in claim 3 wherein said pivot pin is attachedsubstantially perpendicular to said drive shaft means.

5. The pager as claimed in claim 4 wherein the said first distance,between the center of gravity of said weight means and said axis ofrotation, is approximately zero. I

6. The pager as claimed in claim 5 wherein said pager case includesattachment means for mechanically coupling said pager case to a personsbody.

7. A vibratory pager including:

a case; v

a motor mechanically coupled to said case; v

a drive shaft attached to said motor and rotatable by said motor aboutan axis of rotation;

a weight attached to said drive shaft;

said motor being operative in response to receipt of gravityapproximately coincident with the axis of rotation of said weight,- whensaid drive shaft is not rotated and said pager is upright, andnoncoincident when said drive shaft is rotated and said pager isupright.

8. A pager as claimed in claim 7 wherein the connection means includes apivot pin.

1. A vibratory pager including: a pager case; a motor being responsiveto receiving a paging signal and being mechanically coupled to saidpager case; drive shaft means attached to said motor and capable ofbeing rotated about an axis of rotation by said motor; weight means;connection means for attaching said weight means to said drive shaftmeans, such that said weight means has a center of gravity with a firstdistance from the axis of rotation when said drive shaft is not beingrotated, and said weight means moves, when said drive shaft means isbeing rotated, such that the center of gravity of said weight means is asecond distance from the axis of rotation, said second distance beinglarger than said first distance.
 2. The pager as claimed in claim 1wherein the axis of said drive shaft means is coincident with the axisof rotation.
 3. The pager as claimed in claim 2 wherein said connectionmeans includes a pivot pin attached to said drive shaft means.
 4. Thepager as claimed in claim 3 wherein said pivot pin is attachedsubstantially perpendicular to said drive shaft means.
 5. The pager asclaimed in claim 4 wherein the said first distance, between the centerof gravity of said weight means and said axis of rotation, isapproximately zero.
 6. The pager as claimed in claim 5 wherein saidpager case includes attachment means for mechanically coupling saidpager case to a person''s body.
 7. A vibratory pager including: a case;a motor mechanically coupled to said case; a drive shaft attached tosaid motor and rotatable by said motor about an axis of rotation; aweight attached to said drive shaft; said motor being operative inresponse to receipt of a paging signal; said drive shaft means beingcoincident with the axis of rotation; and connection means for attachingsaid weight to said drive shaft such that said weight has a center ofgravity approximately coincident with the axis of rotation of saidweight, when said drive shaft is not rotated and said pager is upright,and noncoincident when said drive shaft is rotated and said pager isupright.
 8. A pager as claimed in claim 7 wherein the connection meansincludes a pivot pin.